<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>Source code</title>
<link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style">
</head>
<body>
<div class="sourceContainer">
<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: PersistentConnection.html 926 2014-09-17 03:05:56Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.net;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.io.IOException;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import javax.annotation.PostConstruct;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import javax.annotation.PreDestroy;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>import org.slf4j.Logger;<a name="line.15"></a>
<span class="sourceLineNo">016</span>import org.slf4j.LoggerFactory;<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span>/**<a name="line.18"></a>
<span class="sourceLineNo">019</span> * Support superclass for clients that want to maintain a persistent connection to some server.<a name="line.19"></a>
<span class="sourceLineNo">020</span> *<a name="line.20"></a>
<span class="sourceLineNo">021</span> * &lt;p&gt;<a name="line.21"></a>
<span class="sourceLineNo">022</span> * This class is suitable for use with any abstract notion of "client", "server", and "connection". Typically<a name="line.22"></a>
<span class="sourceLineNo">023</span> * it would be used to maintain a persistent connection to a remote server over the network. This class<a name="line.23"></a>
<span class="sourceLineNo">024</span> * mainly serves to implement the connection state machine, including an exponential back-off retry timer,<a name="line.24"></a>
<span class="sourceLineNo">025</span> * subclass notifications for state transitions, and guaranteed thread safety.<a name="line.25"></a>
<span class="sourceLineNo">026</span> * &lt;/p&gt;<a name="line.26"></a>
<span class="sourceLineNo">027</span> *<a name="line.27"></a>
<span class="sourceLineNo">028</span> * &lt;p&gt;<a name="line.28"></a>
<span class="sourceLineNo">029</span> * Each instance has a dedicated thread that manages the connection and performs any required work while connected.<a name="line.29"></a>
<span class="sourceLineNo">030</span> * The lifecycle of a connection is delimited by calls (by this thread) to the subclass methods<a name="line.30"></a>
<span class="sourceLineNo">031</span> * {@link #createConnection createConnection()} and {@link #cleanupConnection cleanupConnection()}.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * The actual per-connection work is performed by {@link #handleConnection handleConnection()}.<a name="line.32"></a>
<span class="sourceLineNo">033</span> * Each connection has an associated connection context (defined by the subclass) and passed to these methods.<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;/p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> *<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> * The subclass is also notified of state machine transitions via the state transition methods<a name="line.37"></a>
<span class="sourceLineNo">038</span> * {@link #started started()}, {@link #stopped stopped()}, {@link #connectionSuccessful connectionSuccessful()},<a name="line.38"></a>
<span class="sourceLineNo">039</span> * {@link #connectionFailed connectionFailed()}, and {@link #connectionEnded connectionEnded()};<a name="line.39"></a>
<span class="sourceLineNo">040</span> * all of these methods are invoked by the background thread.<a name="line.40"></a>
<span class="sourceLineNo">041</span> * &lt;/p&gt;<a name="line.41"></a>
<span class="sourceLineNo">042</span> *<a name="line.42"></a>
<span class="sourceLineNo">043</span> * @param &lt;C&gt; connection context type<a name="line.43"></a>
<span class="sourceLineNo">044</span> */<a name="line.44"></a>
<span class="sourceLineNo">045</span>public abstract class PersistentConnection&lt;C&gt; {<a name="line.45"></a>
<span class="sourceLineNo">046</span><a name="line.46"></a>
<span class="sourceLineNo">047</span>    /**<a name="line.47"></a>
<span class="sourceLineNo">048</span>     * Default minimum restart delay.<a name="line.48"></a>
<span class="sourceLineNo">049</span>     *<a name="line.49"></a>
<span class="sourceLineNo">050</span>     * @see #setMinRestartDelay<a name="line.50"></a>
<span class="sourceLineNo">051</span>     */<a name="line.51"></a>
<span class="sourceLineNo">052</span>    public static final long DEFAULT_MIN_RESTART_DELAY = 10 * 1000L;<a name="line.52"></a>
<span class="sourceLineNo">053</span><a name="line.53"></a>
<span class="sourceLineNo">054</span>    /**<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * Default maximum restart delay.<a name="line.55"></a>
<span class="sourceLineNo">056</span>     *<a name="line.56"></a>
<span class="sourceLineNo">057</span>     * @see #setMaxRestartDelay<a name="line.57"></a>
<span class="sourceLineNo">058</span>     */<a name="line.58"></a>
<span class="sourceLineNo">059</span>    public static final long DEFAULT_MAX_RESTART_DELAY = 10 * 60 * 1000L;<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span>    protected final Logger log = LoggerFactory.getLogger(this.getClass());<a name="line.61"></a>
<span class="sourceLineNo">062</span><a name="line.62"></a>
<span class="sourceLineNo">063</span>    private long minRestartDelay = DEFAULT_MIN_RESTART_DELAY;<a name="line.63"></a>
<span class="sourceLineNo">064</span>    private long maxRestartDelay = DEFAULT_MAX_RESTART_DELAY;<a name="line.64"></a>
<span class="sourceLineNo">065</span><a name="line.65"></a>
<span class="sourceLineNo">066</span>    private volatile ClientThread thread;<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>// Properties<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>    /**<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * Set the minimum restart delay after being disconnected from the server.<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * Default is {@link #DEFAULT_MIN_RESTART_DELAY} ({@value #DEFAULT_MIN_RESTART_DELAY}}ms).<a name="line.72"></a>
<span class="sourceLineNo">073</span>     *<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * @param minRestartDelay minimum restart delay in milliseconds<a name="line.74"></a>
<span class="sourceLineNo">075</span>     */<a name="line.75"></a>
<span class="sourceLineNo">076</span>    public void setMinRestartDelay(long minRestartDelay) {<a name="line.76"></a>
<span class="sourceLineNo">077</span>        this.minRestartDelay = minRestartDelay;<a name="line.77"></a>
<span class="sourceLineNo">078</span>    }<a name="line.78"></a>
<span class="sourceLineNo">079</span>    public long getMinRestartDelay() {<a name="line.79"></a>
<span class="sourceLineNo">080</span>        return this.minRestartDelay;<a name="line.80"></a>
<span class="sourceLineNo">081</span>    }<a name="line.81"></a>
<span class="sourceLineNo">082</span><a name="line.82"></a>
<span class="sourceLineNo">083</span>    /**<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * Set the maximum restart delay after being disconnected from the server.<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * Default is {@link #DEFAULT_MAX_RESTART_DELAY} ({@value #DEFAULT_MAX_RESTART_DELAY}}ms).<a name="line.85"></a>
<span class="sourceLineNo">086</span>     *<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * @param maxRestartDelay maximum restart delay in milliseconds<a name="line.87"></a>
<span class="sourceLineNo">088</span>     */<a name="line.88"></a>
<span class="sourceLineNo">089</span>    public void setMaxRestartDelay(long maxRestartDelay) {<a name="line.89"></a>
<span class="sourceLineNo">090</span>        this.maxRestartDelay = maxRestartDelay;<a name="line.90"></a>
<span class="sourceLineNo">091</span>    }<a name="line.91"></a>
<span class="sourceLineNo">092</span>    public long getMaxRestartDelay() {<a name="line.92"></a>
<span class="sourceLineNo">093</span>        return this.maxRestartDelay;<a name="line.93"></a>
<span class="sourceLineNo">094</span>    }<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span>    /**<a name="line.96"></a>
<span class="sourceLineNo">097</span>     * Get the name to use for the network client thread.<a name="line.97"></a>
<span class="sourceLineNo">098</span>     *<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * &lt;p&gt;<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * The implementation in {@link PersistentConnection} returns {@code this.toString() + " thread"}.<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * &lt;/p&gt;<a name="line.101"></a>
<span class="sourceLineNo">102</span>     */<a name="line.102"></a>
<span class="sourceLineNo">103</span>    protected String getThreadName() {<a name="line.103"></a>
<span class="sourceLineNo">104</span>        return this + " thread";<a name="line.104"></a>
<span class="sourceLineNo">105</span>    }<a name="line.105"></a>
<span class="sourceLineNo">106</span><a name="line.106"></a>
<span class="sourceLineNo">107</span>// Lifecycle<a name="line.107"></a>
<span class="sourceLineNo">108</span><a name="line.108"></a>
<span class="sourceLineNo">109</span>    /**<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * Start this instance. This starts the background thread, which initiates the first connection attempt.<a name="line.110"></a>
<span class="sourceLineNo">111</span>     *<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * &lt;p&gt;<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * If this instance is already started, nothing happens.<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * &lt;/p&gt;<a name="line.114"></a>
<span class="sourceLineNo">115</span>     */<a name="line.115"></a>
<span class="sourceLineNo">116</span>    @PostConstruct<a name="line.116"></a>
<span class="sourceLineNo">117</span>    public synchronized void start() {<a name="line.117"></a>
<span class="sourceLineNo">118</span>        if (this.thread != null)<a name="line.118"></a>
<span class="sourceLineNo">119</span>            return;<a name="line.119"></a>
<span class="sourceLineNo">120</span>        this.thread = new ClientThread();<a name="line.120"></a>
<span class="sourceLineNo">121</span>        this.thread.start();<a name="line.121"></a>
<span class="sourceLineNo">122</span>    }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>    /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * Stop this client.<a name="line.125"></a>
<span class="sourceLineNo">126</span>     *<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * &lt;p&gt;<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * This method simply {@linkplain Thread#interrupt interrupts} the background thread, if any.<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * &lt;/p&gt;<a name="line.129"></a>
<span class="sourceLineNo">130</span>     */<a name="line.130"></a>
<span class="sourceLineNo">131</span>    @PreDestroy<a name="line.131"></a>
<span class="sourceLineNo">132</span>    public synchronized void stop() {<a name="line.132"></a>
<span class="sourceLineNo">133</span>        if (this.thread != null) {<a name="line.133"></a>
<span class="sourceLineNo">134</span>            this.log.info("stopping " + this + " thread " + this.thread);<a name="line.134"></a>
<span class="sourceLineNo">135</span>            this.thread.interrupt();<a name="line.135"></a>
<span class="sourceLineNo">136</span>            this.thread = null;<a name="line.136"></a>
<span class="sourceLineNo">137</span>        }<a name="line.137"></a>
<span class="sourceLineNo">138</span>    }<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>    /**<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * Determine if this instance is started.<a name="line.141"></a>
<span class="sourceLineNo">142</span>     */<a name="line.142"></a>
<span class="sourceLineNo">143</span>    public final synchronized boolean isRunning() {<a name="line.143"></a>
<span class="sourceLineNo">144</span>        return this.thread != null;<a name="line.144"></a>
<span class="sourceLineNo">145</span>    }<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>// Main loop<a name="line.147"></a>
<span class="sourceLineNo">148</span><a name="line.148"></a>
<span class="sourceLineNo">149</span>    private void poll() {<a name="line.149"></a>
<span class="sourceLineNo">150</span><a name="line.150"></a>
<span class="sourceLineNo">151</span>        // Loop reconnecting<a name="line.151"></a>
<span class="sourceLineNo">152</span>        for (long restartDelay = this.minRestartDelay; this.thread == Thread.currentThread(); ) {<a name="line.152"></a>
<span class="sourceLineNo">153</span><a name="line.153"></a>
<span class="sourceLineNo">154</span>            // Do one connection cycle<a name="line.154"></a>
<span class="sourceLineNo">155</span>            if (this.doConnection())<a name="line.155"></a>
<span class="sourceLineNo">156</span>                restartDelay = this.minRestartDelay;<a name="line.156"></a>
<span class="sourceLineNo">157</span><a name="line.157"></a>
<span class="sourceLineNo">158</span>            // Check whether we should exit<a name="line.158"></a>
<span class="sourceLineNo">159</span>            if (this.thread != Thread.currentThread()) {<a name="line.159"></a>
<span class="sourceLineNo">160</span>                this.log.info(this + " thread exiting");<a name="line.160"></a>
<span class="sourceLineNo">161</span>                break;<a name="line.161"></a>
<span class="sourceLineNo">162</span>            }<a name="line.162"></a>
<span class="sourceLineNo">163</span><a name="line.163"></a>
<span class="sourceLineNo">164</span>            // Pause a while before trying to connect again<a name="line.164"></a>
<span class="sourceLineNo">165</span>            try {<a name="line.165"></a>
<span class="sourceLineNo">166</span>                this.log.info(this + " pausing " + restartDelay + "ms before next connection attempt");<a name="line.166"></a>
<span class="sourceLineNo">167</span>                Thread.sleep(restartDelay);<a name="line.167"></a>
<span class="sourceLineNo">168</span>            } catch (InterruptedException e) {<a name="line.168"></a>
<span class="sourceLineNo">169</span>                this.log.info(this + " thread exiting due to interrupt");<a name="line.169"></a>
<span class="sourceLineNo">170</span>                break;<a name="line.170"></a>
<span class="sourceLineNo">171</span>            }<a name="line.171"></a>
<span class="sourceLineNo">172</span><a name="line.172"></a>
<span class="sourceLineNo">173</span>            // Increase restart delay for next time<a name="line.173"></a>
<span class="sourceLineNo">174</span>            restartDelay = Math.max(this.minRestartDelay, Math.min(restartDelay * 2, this.maxRestartDelay));<a name="line.174"></a>
<span class="sourceLineNo">175</span>        }<a name="line.175"></a>
<span class="sourceLineNo">176</span>    }<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>    // Perform one connection cycle<a name="line.178"></a>
<span class="sourceLineNo">179</span>    private boolean doConnection() {<a name="line.179"></a>
<span class="sourceLineNo">180</span><a name="line.180"></a>
<span class="sourceLineNo">181</span>        // Get this ClientThread object<a name="line.181"></a>
<span class="sourceLineNo">182</span>        final PersistentConnection&lt;?&gt;.ClientThread thisClientThread = (PersistentConnection&lt;?&gt;.ClientThread)Thread.currentThread();<a name="line.182"></a>
<span class="sourceLineNo">183</span><a name="line.183"></a>
<span class="sourceLineNo">184</span>        // Create new connection to server<a name="line.184"></a>
<span class="sourceLineNo">185</span>        try {<a name="line.185"></a>
<span class="sourceLineNo">186</span>            thisClientThread.createConnection();<a name="line.186"></a>
<span class="sourceLineNo">187</span>        } catch (Exception e) {<a name="line.187"></a>
<span class="sourceLineNo">188</span>            this.connectionFailed(e);<a name="line.188"></a>
<span class="sourceLineNo">189</span>            return false;<a name="line.189"></a>
<span class="sourceLineNo">190</span>        }<a name="line.190"></a>
<span class="sourceLineNo">191</span>        this.connectionSuccessful();<a name="line.191"></a>
<span class="sourceLineNo">192</span>        try {<a name="line.192"></a>
<span class="sourceLineNo">193</span><a name="line.193"></a>
<span class="sourceLineNo">194</span>            // Check whether we should exit<a name="line.194"></a>
<span class="sourceLineNo">195</span>            if (this.thread != Thread.currentThread())<a name="line.195"></a>
<span class="sourceLineNo">196</span>                return true;<a name="line.196"></a>
<span class="sourceLineNo">197</span><a name="line.197"></a>
<span class="sourceLineNo">198</span>            // Handle connection<a name="line.198"></a>
<span class="sourceLineNo">199</span>            Exception exception = null;<a name="line.199"></a>
<span class="sourceLineNo">200</span>            try {<a name="line.200"></a>
<span class="sourceLineNo">201</span>                thisClientThread.handleConnection();<a name="line.201"></a>
<span class="sourceLineNo">202</span>            } catch (Exception e) {<a name="line.202"></a>
<span class="sourceLineNo">203</span>                exception = e;<a name="line.203"></a>
<span class="sourceLineNo">204</span>            }<a name="line.204"></a>
<span class="sourceLineNo">205</span>            this.connectionEnded(exception);<a name="line.205"></a>
<span class="sourceLineNo">206</span><a name="line.206"></a>
<span class="sourceLineNo">207</span>            // Done<a name="line.207"></a>
<span class="sourceLineNo">208</span>            return true;<a name="line.208"></a>
<span class="sourceLineNo">209</span>        } finally {<a name="line.209"></a>
<span class="sourceLineNo">210</span><a name="line.210"></a>
<span class="sourceLineNo">211</span>            // Clean up connection<a name="line.211"></a>
<span class="sourceLineNo">212</span>            thisClientThread.cleanupConnection();<a name="line.212"></a>
<span class="sourceLineNo">213</span>        }<a name="line.213"></a>
<span class="sourceLineNo">214</span>    }<a name="line.214"></a>
<span class="sourceLineNo">215</span><a name="line.215"></a>
<span class="sourceLineNo">216</span>// Connection Callbacks<a name="line.216"></a>
<span class="sourceLineNo">217</span><a name="line.217"></a>
<span class="sourceLineNo">218</span>    /**<a name="line.218"></a>
<span class="sourceLineNo">219</span>     * Create a new server connection.<a name="line.219"></a>
<span class="sourceLineNo">220</span>     *<a name="line.220"></a>
<span class="sourceLineNo">221</span>     * &lt;p&gt;<a name="line.221"></a>
<span class="sourceLineNo">222</span>     * If this method throws an unchecked exception, {@link #stopped stopped()} will be invoked with the exception<a name="line.222"></a>
<span class="sourceLineNo">223</span>     * and this instance will be automatically stopped.<a name="line.223"></a>
<span class="sourceLineNo">224</span>     * &lt;/p&gt;<a name="line.224"></a>
<span class="sourceLineNo">225</span>     *<a name="line.225"></a>
<span class="sourceLineNo">226</span>     * @throws InterruptedException if interrupted<a name="line.226"></a>
<span class="sourceLineNo">227</span>     * @throws IOException if there is a problem establishing the connection<a name="line.227"></a>
<span class="sourceLineNo">228</span>     * @return context for the connection, which will be supplied to {@link #handleConnection handleConnection()}<a name="line.228"></a>
<span class="sourceLineNo">229</span>     * and {@link #cleanupConnection cleanupConnection()}<a name="line.229"></a>
<span class="sourceLineNo">230</span>     */<a name="line.230"></a>
<span class="sourceLineNo">231</span>    protected abstract C createConnection() throws InterruptedException, IOException;<a name="line.231"></a>
<span class="sourceLineNo">232</span><a name="line.232"></a>
<span class="sourceLineNo">233</span>    /**<a name="line.233"></a>
<span class="sourceLineNo">234</span>     * Handle one server connection.<a name="line.234"></a>
<span class="sourceLineNo">235</span>     *<a name="line.235"></a>
<span class="sourceLineNo">236</span>     * &lt;p&gt;<a name="line.236"></a>
<span class="sourceLineNo">237</span>     * This method may either throw an exception or return normally; the only difference is whether<a name="line.237"></a>
<span class="sourceLineNo">238</span>     * {@link #connectionEnded connectionEnded()} is invoked with a non-null parameter or not.<a name="line.238"></a>
<span class="sourceLineNo">239</span>     * &lt;/p&gt;<a name="line.239"></a>
<span class="sourceLineNo">240</span>     *<a name="line.240"></a>
<span class="sourceLineNo">241</span>     * &lt;p&gt;<a name="line.241"></a>
<span class="sourceLineNo">242</span>     * Ideally this method should never return normally. However, in practice there are legitimate reasons to do so,<a name="line.242"></a>
<span class="sourceLineNo">243</span>     * for example, if there is an application-level error that indicates the particular connection is no longer usable.<a name="line.243"></a>
<span class="sourceLineNo">244</span>     * &lt;/p&gt;<a name="line.244"></a>
<span class="sourceLineNo">245</span>     *<a name="line.245"></a>
<span class="sourceLineNo">246</span>     * &lt;p&gt;<a name="line.246"></a>
<span class="sourceLineNo">247</span>     * If this method throws an unchecked exception, {@link #stopped stopped()} will be invoked with the exception<a name="line.247"></a>
<span class="sourceLineNo">248</span>     * and this instance will be automatically stopped.<a name="line.248"></a>
<span class="sourceLineNo">249</span>     * &lt;/p&gt;<a name="line.249"></a>
<span class="sourceLineNo">250</span>     *<a name="line.250"></a>
<span class="sourceLineNo">251</span>     * @param connectionContext connection context returned from {@link #createConnection} when this connection was created<a name="line.251"></a>
<span class="sourceLineNo">252</span>     * @throws InterruptedException if interrupted<a name="line.252"></a>
<span class="sourceLineNo">253</span>     * @throws IOException if there is a problem during the connection or the connection fails<a name="line.253"></a>
<span class="sourceLineNo">254</span>     */<a name="line.254"></a>
<span class="sourceLineNo">255</span>    protected abstract void handleConnection(C connectionContext) throws InterruptedException, IOException;<a name="line.255"></a>
<span class="sourceLineNo">256</span><a name="line.256"></a>
<span class="sourceLineNo">257</span>    /**<a name="line.257"></a>
<span class="sourceLineNo">258</span>     * Perform cleanup after a server connection ends. This method should close any open sockets, etc.<a name="line.258"></a>
<span class="sourceLineNo">259</span>     *<a name="line.259"></a>
<span class="sourceLineNo">260</span>     * &lt;p&gt;<a name="line.260"></a>
<span class="sourceLineNo">261</span>     * For each successful invocation of {@link #createConnection} there is guaranteed be exactly<a name="line.261"></a>
<span class="sourceLineNo">262</span>     * one invocation of this method.<a name="line.262"></a>
<span class="sourceLineNo">263</span>     * &lt;/p&gt;<a name="line.263"></a>
<span class="sourceLineNo">264</span>     *<a name="line.264"></a>
<span class="sourceLineNo">265</span>     * &lt;p&gt;<a name="line.265"></a>
<span class="sourceLineNo">266</span>     * The {@code exception} parameter indicates either a normal return (if null) or thrown exception (if not null) from<a name="line.266"></a>
<span class="sourceLineNo">267</span>     * {@link #handleConnection handleConnection()}. In any case, this instance will automatically begin attempting to reconnect<a name="line.267"></a>
<span class="sourceLineNo">268</span>     * when this method returns.<a name="line.268"></a>
<span class="sourceLineNo">269</span>     * &lt;/p&gt;<a name="line.269"></a>
<span class="sourceLineNo">270</span>     *<a name="line.270"></a>
<span class="sourceLineNo">271</span>     * &lt;p&gt;<a name="line.271"></a>
<span class="sourceLineNo">272</span>     * If this method throws an unchecked exception, {@link #stopped stopped()} will be invoked with the exception<a name="line.272"></a>
<span class="sourceLineNo">273</span>     * and this instance will be automatically stopped.<a name="line.273"></a>
<span class="sourceLineNo">274</span>     * &lt;/p&gt;<a name="line.274"></a>
<span class="sourceLineNo">275</span>     *<a name="line.275"></a>
<span class="sourceLineNo">276</span>     * &lt;p&gt;<a name="line.276"></a>
<span class="sourceLineNo">277</span>     * The implementation in {@link PersistentConnection} does nothing. Subclasses should override if necessary.<a name="line.277"></a>
<span class="sourceLineNo">278</span>     * &lt;/p&gt;<a name="line.278"></a>
<span class="sourceLineNo">279</span>     *<a name="line.279"></a>
<span class="sourceLineNo">280</span>     * @param connectionContext connection context returned from {@link #createConnection} when this connection was created<a name="line.280"></a>
<span class="sourceLineNo">281</span>     */<a name="line.281"></a>
<span class="sourceLineNo">282</span>    protected void cleanupConnection(C connectionContext) {<a name="line.282"></a>
<span class="sourceLineNo">283</span>    }<a name="line.283"></a>
<span class="sourceLineNo">284</span><a name="line.284"></a>
<span class="sourceLineNo">285</span>// State Machine Transitions<a name="line.285"></a>
<span class="sourceLineNo">286</span><a name="line.286"></a>
<span class="sourceLineNo">287</span>    /**<a name="line.287"></a>
<span class="sourceLineNo">288</span>     * State machine transition: this instance was started via {@link #start start()}.<a name="line.288"></a>
<span class="sourceLineNo">289</span>     *<a name="line.289"></a>
<span class="sourceLineNo">290</span>     * &lt;p&gt;<a name="line.290"></a>
<span class="sourceLineNo">291</span>     * The implementation in {@link PersistentConnection} does nothing; subclasses may override.<a name="line.291"></a>
<span class="sourceLineNo">292</span>     * &lt;/p&gt;<a name="line.292"></a>
<span class="sourceLineNo">293</span>     */<a name="line.293"></a>
<span class="sourceLineNo">294</span>    protected void started() {<a name="line.294"></a>
<span class="sourceLineNo">295</span>    }<a name="line.295"></a>
<span class="sourceLineNo">296</span><a name="line.296"></a>
<span class="sourceLineNo">297</span>    /**<a name="line.297"></a>
<span class="sourceLineNo">298</span>     * State machine transition: this instance was stopped via {@link #stop stop()} of because or<a name="line.298"></a>
<span class="sourceLineNo">299</span>     * an unchecked exception was thrown by one of the subclass methods.<a name="line.299"></a>
<span class="sourceLineNo">300</span>     *<a name="line.300"></a>
<span class="sourceLineNo">301</span>     * &lt;p&gt;<a name="line.301"></a>
<span class="sourceLineNo">302</span>     * The implementation in {@link PersistentConnection} does nothing; subclasses may override.<a name="line.302"></a>
<span class="sourceLineNo">303</span>     * &lt;/p&gt;<a name="line.303"></a>
<span class="sourceLineNo">304</span>     *<a name="line.304"></a>
<span class="sourceLineNo">305</span>     * @param t unexpected exception, or null if this instance was stopped via {@link #stop stop()}.<a name="line.305"></a>
<span class="sourceLineNo">306</span>     */<a name="line.306"></a>
<span class="sourceLineNo">307</span>    protected void stopped(Throwable t) {<a name="line.307"></a>
<span class="sourceLineNo">308</span>    }<a name="line.308"></a>
<span class="sourceLineNo">309</span><a name="line.309"></a>
<span class="sourceLineNo">310</span>    /**<a name="line.310"></a>
<span class="sourceLineNo">311</span>     * State machine transition: initialization of a new connection via {@link #createConnection} was successful<a name="line.311"></a>
<span class="sourceLineNo">312</span>     * and we are connected to the server.<a name="line.312"></a>
<span class="sourceLineNo">313</span>     *<a name="line.313"></a>
<span class="sourceLineNo">314</span>     * &lt;p&gt;<a name="line.314"></a>
<span class="sourceLineNo">315</span>     * The implementation in {@link PersistentConnection} does nothing; subclasses may override.<a name="line.315"></a>
<span class="sourceLineNo">316</span>     * &lt;/p&gt;<a name="line.316"></a>
<span class="sourceLineNo">317</span>     */<a name="line.317"></a>
<span class="sourceLineNo">318</span>    protected void connectionSuccessful() {<a name="line.318"></a>
<span class="sourceLineNo">319</span>    }<a name="line.319"></a>
<span class="sourceLineNo">320</span><a name="line.320"></a>
<span class="sourceLineNo">321</span>    /**<a name="line.321"></a>
<span class="sourceLineNo">322</span>     * State machine transition: initialization of a new connection via {@link #createConnection} failed due to an exception.<a name="line.322"></a>
<span class="sourceLineNo">323</span>     * This instance will automatically attempt to retry.<a name="line.323"></a>
<span class="sourceLineNo">324</span>     *<a name="line.324"></a>
<span class="sourceLineNo">325</span>     * &lt;p&gt;<a name="line.325"></a>
<span class="sourceLineNo">326</span>     * The implementation in {@link PersistentConnection} does nothing; subclasses may override.<a name="line.326"></a>
<span class="sourceLineNo">327</span>     * &lt;/p&gt;<a name="line.327"></a>
<span class="sourceLineNo">328</span>     *<a name="line.328"></a>
<span class="sourceLineNo">329</span>     * @param e Exception thrown by {@link #createConnection}.<a name="line.329"></a>
<span class="sourceLineNo">330</span>     */<a name="line.330"></a>
<span class="sourceLineNo">331</span>    protected void connectionFailed(Exception e) {<a name="line.331"></a>
<span class="sourceLineNo">332</span>    }<a name="line.332"></a>
<span class="sourceLineNo">333</span><a name="line.333"></a>
<span class="sourceLineNo">334</span>    /**<a name="line.334"></a>
<span class="sourceLineNo">335</span>     * State machine transition: an established connection to the server has ended. This indicates either normal<a name="line.335"></a>
<span class="sourceLineNo">336</span>     * return or a thrown an exception from {@link #handleConnection handleConnection()}.<a name="line.336"></a>
<span class="sourceLineNo">337</span>     * This instance will automatically attempt to reconnect.<a name="line.337"></a>
<span class="sourceLineNo">338</span>     *<a name="line.338"></a>
<span class="sourceLineNo">339</span>     * &lt;p&gt;<a name="line.339"></a>
<span class="sourceLineNo">340</span>     * The implementation in {@link PersistentConnection} does nothing; subclasses may override.<a name="line.340"></a>
<span class="sourceLineNo">341</span>     * &lt;/p&gt;<a name="line.341"></a>
<span class="sourceLineNo">342</span>     *<a name="line.342"></a>
<span class="sourceLineNo">343</span>     * @param e Exception thrown by {@link #handleConnection handleConnection()},<a name="line.343"></a>
<span class="sourceLineNo">344</span>     *  or null if {@link #handleConnection handleConnection()} returned normally<a name="line.344"></a>
<span class="sourceLineNo">345</span>     */<a name="line.345"></a>
<span class="sourceLineNo">346</span>    protected void connectionEnded(Exception e) {<a name="line.346"></a>
<span class="sourceLineNo">347</span>    }<a name="line.347"></a>
<span class="sourceLineNo">348</span><a name="line.348"></a>
<span class="sourceLineNo">349</span>// ClientThread<a name="line.349"></a>
<span class="sourceLineNo">350</span><a name="line.350"></a>
<span class="sourceLineNo">351</span>    private class ClientThread extends Thread {<a name="line.351"></a>
<span class="sourceLineNo">352</span><a name="line.352"></a>
<span class="sourceLineNo">353</span>        private volatile C context;<a name="line.353"></a>
<span class="sourceLineNo">354</span><a name="line.354"></a>
<span class="sourceLineNo">355</span>        ClientThread() {<a name="line.355"></a>
<span class="sourceLineNo">356</span>            super(PersistentConnection.this.getThreadName());<a name="line.356"></a>
<span class="sourceLineNo">357</span>        }<a name="line.357"></a>
<span class="sourceLineNo">358</span><a name="line.358"></a>
<span class="sourceLineNo">359</span>        @Override<a name="line.359"></a>
<span class="sourceLineNo">360</span>        public void run() {<a name="line.360"></a>
<span class="sourceLineNo">361</span>            Throwable exception = null;<a name="line.361"></a>
<span class="sourceLineNo">362</span>            try {<a name="line.362"></a>
<span class="sourceLineNo">363</span>                PersistentConnection.this.log.info(PersistentConnection.this + " thread starting");<a name="line.363"></a>
<span class="sourceLineNo">364</span>                PersistentConnection.this.started();<a name="line.364"></a>
<span class="sourceLineNo">365</span>                PersistentConnection.this.poll();<a name="line.365"></a>
<span class="sourceLineNo">366</span>            } catch (Throwable t) {<a name="line.366"></a>
<span class="sourceLineNo">367</span>                exception = t;<a name="line.367"></a>
<span class="sourceLineNo">368</span>                if (t instanceof Error)<a name="line.368"></a>
<span class="sourceLineNo">369</span>                    throw (Error)t;<a name="line.369"></a>
<span class="sourceLineNo">370</span>                if (t instanceof RuntimeException)<a name="line.370"></a>
<span class="sourceLineNo">371</span>                    throw (RuntimeException)t;<a name="line.371"></a>
<span class="sourceLineNo">372</span>                throw new RuntimeException(t);<a name="line.372"></a>
<span class="sourceLineNo">373</span>            } finally {<a name="line.373"></a>
<span class="sourceLineNo">374</span>                synchronized (PersistentConnection.this) {<a name="line.374"></a>
<span class="sourceLineNo">375</span>                    if (PersistentConnection.this.thread == this)<a name="line.375"></a>
<span class="sourceLineNo">376</span>                        PersistentConnection.this.thread = null;<a name="line.376"></a>
<span class="sourceLineNo">377</span>                }<a name="line.377"></a>
<span class="sourceLineNo">378</span>                PersistentConnection.this.stopped(exception);<a name="line.378"></a>
<span class="sourceLineNo">379</span>            }<a name="line.379"></a>
<span class="sourceLineNo">380</span>        }<a name="line.380"></a>
<span class="sourceLineNo">381</span><a name="line.381"></a>
<span class="sourceLineNo">382</span>        void createConnection() throws Exception {<a name="line.382"></a>
<span class="sourceLineNo">383</span>            this.context = PersistentConnection.this.createConnection();<a name="line.383"></a>
<span class="sourceLineNo">384</span>        }<a name="line.384"></a>
<span class="sourceLineNo">385</span><a name="line.385"></a>
<span class="sourceLineNo">386</span>        void handleConnection() throws Exception {<a name="line.386"></a>
<span class="sourceLineNo">387</span>            PersistentConnection.this.handleConnection(this.context);<a name="line.387"></a>
<span class="sourceLineNo">388</span>        }<a name="line.388"></a>
<span class="sourceLineNo">389</span><a name="line.389"></a>
<span class="sourceLineNo">390</span>        void cleanupConnection() {<a name="line.390"></a>
<span class="sourceLineNo">391</span>            PersistentConnection.this.cleanupConnection(this.context);<a name="line.391"></a>
<span class="sourceLineNo">392</span>        }<a name="line.392"></a>
<span class="sourceLineNo">393</span>    }<a name="line.393"></a>
<span class="sourceLineNo">394</span>}<a name="line.394"></a>
<span class="sourceLineNo">395</span><a name="line.395"></a>




























































</pre>
</div>
</body>
</html>
